6.3.2 Populations and Sustainability Flashcards
Limiting factor
environmental resource or constraint that limits population growth
example of limiting factor
food availability
water availability
habitat availability
competition between organisms for resources
build up of toxic by products of metabolism
disease
predators
Phase 1 of population growth graph
slow growth
small numbers initially present reproduce increasing the total population
birth rate is higher than death rate
Phase 2 of population growth graph
rapid growth
number of breeding individuals increases
total population multiplies exponentially
no limiting factors
Phase 3 of population growth graph
stable state
further population growth is prevented by external factors
population size fluctuates due to limiting factors such as predators but overall size remains stable
birth rate = death rate
carrying capacity
maximum population size that an environment can support
Immigration
movement of individuals into a particular area increasing population size
emigration
movement of individual organisms away from a particular area decreasing the population size
Density independent factors
factors that have effect on whole population regardless of its size
earthquakes, fires, volcanic eruptions, storms
what do density independent factors cause
remove whole populations of species from a region
dramatically change population size
interspecific competition definition
competition between different species
intraspecific competition definition
competition between members of the same species
when does interspecific competition occur
when 2 or more different species of organism compete for the same resource
what does interspecific competition cause
reduction in resources available to both populations
due to less food organisms will have less energy for growth and reproduction so results in smaller populations
what does interspecific competition cause if one is better adapted
less well adapted species will be outcompeted and if conditions remain the same less well adapted species will decline in numbers until it no longer exists in that habitat
competitive exclusion principle
2 species competing for limited resources, the one that uses resources more effectively will eliminate the other
Red and Grey squirrels
undergo interspecific competition in uk for food and territory
grey squirrel was native to north America but introduced to uk so quickly increased in numbers and resulted in decrease in red squirrel as grey can eat wider range of food and larger so can store more fat
increases change of survival and ability to reproduce so increases its population
this causes decrease in resources for red squirrel reducing ability to survive and reproduce
stage 1 of intraspecific competition
when resource is plentiful in habitat all organisms have enough of the resource to survive and reproduce
- increase in population size
stage 2 of intraspecific competition
due to increase in population size, many more individuals to share food and space available
resources now limited - not enough for all organisms to survive
- decrease in population size
stage 3 of intraspecific competition
less competition as smaller population
less organisms competing for same resource
more organisms survive and reproduce
- increase in population size
predation
an organism kills and eats another organism
stage 1 of predator prey relationships
increase in prey population provides more food for predators = more can survive and reproduce= increase in predator population
stage 2 of predator prey relationships
increase in predator population= eat more prey= decline in prey population
death rate of prey > birth rate of prey
stage 3 of predator prey relationships
reduced prey population can’t support large predator population
intraspecific competition for food increases = decrease in size of predator population
stage 4 of predator prey relationships
reduced predator numbers results in less prey being killed = more prey survive and reproduce = prey population increases
Conservation
maintenance of biodiversity through human action and management
- dynamic
needs to adapt to constant change
sustainable development in conservation
management of ecosystems so natural resources in them can be used without running out
reclamation
process of restoring ecosystems that have been damaged or destroyed
what techniques does reclamation involve
controlled burning of areas of rainforest to halt succession and increase biodiversity
preservation
protection of an area by restricting or banning human interference so ecosystem is kept in its original state
when is preservation commonly used
when preserving ecologically, archaeologically or paleontologically sensitive resources that can be easily damaged or destroyed by disturbances
economic importance of conservation
provide resources that humans need to survive and to provide income
e.g rainforest species provide medicinal drugs, clothes and food that can be traded
other are used for timber and paper production
social importance of conservation
many people enjoy natural beauty of wild ecosystems as well as using them mor beneficial health activities
e. walking, cycling, climbing
ethical importance of conservation
all organisms have right to exist and most play important role within ecosystem
many people believe we shouldn’t have right to decide which organisms can survive and which we can live without
- have moral responsibility for future generations to conserve wide variety of existing ecosystems
aims of sustainability
preserve environment
ensure resources are available for future generations
allow humans in all societies to live comfortably
enable less economically developed countries to develop through exploiting their natural resources
create more even balance in consumption of these resources between more economically developed countries and less economically developed countries
small-scale timber production
use of coppicing
- tree trunk is cut close to the ground and new shoots from from the cut surface and mature
- eventually these shoots are cut and more are produced
- shoots are used for things like fencing
how does rotational coppicing maintain biodiversity
trees never grow tall enough to block out the light
what is rotational coppicing
woodland divided into sections
trees are only cut in particular section until all have been coppiced
coppicing then begins in another area to allow new coppiced trees to grow
continues until reach 1st coppiced trees which will have grown into mature sized trees
pollarding
similar to coppicing but trunk is cut higher up to prevent deer and animals eating new shoots as they appear
to ensure large scale timber production is sustainable what do the companies do
- selective cutting- only cut largest trees
- replace trees through replanting to ensure biodiversity and mineral and water cycles remain
- plant trees an optimal distance apart to reduce competition = higher yield as more wood produced per tree
- manage pests and pathogens to maximise yield
- ensure areas of forest remain for indigenous people
major disadvantage of large scale timber production
habitats are destroyed, soil minerals are reduced and bare soil left is susceptible to erosion and trees bind soil together and remove water and maintain nutrient levels
what technique is used for large scale timber production
felling
felled trees are destroyed and don’t grow back
sustainable fishing techniques
- limit numbers on certain species of fish that are allowed to be caught in a certain area - allows fish to reproduce sufficiently to allow them to maintain population
- use of larger nets to allow immature fish to escape so only mature are caught allowing reproduction to continue
- only allow commercial and recreational fishing to happen at certain times of the year - protects breeding season of some fish to allow them to increase numbers
- introduction of fish farming to maintain supply of protein food whilst preventing loss of wild species
